1. Field of the Invention
The present invention relates to an in-circuit emulator, and more particularly to a probe using a flexible printed circuit board.
2. Description of the Related Art
For the purpose of assisting in the understanding of the present invention, a conventional probe for the in-circuit emulator of the type relevant to the present invention is first explained with reference to the related drawings.
FIG. 1 shows in sectional view a conventional probe of the kind to which the present invention relates. As shown in FIG. 1, a target board conductor line 12 is provided on a target board 10 and a dummy chip 18 to which a dummy chip lead 14 is fixed is provided on this target board conductor line 12. The dummy chip 16 detachably receives a probe head 18 from which a flat cable 19 is drawn out.
FIG. 2 shows in perspective view a microcomputer program development system to which the probe shown in FIG. 1 is connected. As seen in FIG. 2, the target board 10 carrying thereon the dummy chip 16 is prearranged, and the flat cable 19 having the probe head 18 at the foremost end is connected to an in-circuit emulator 20 which in turn is connected to a personal computer 22.
First, an object of using an in-circuit emulator (hereinafter referred to as an "ICE") is briefly explained. For producing an equipment using a microcomputer, it is required to prepare a hardware of the equipment and a software for the microcomputer for controlling the hardware. In order to realize the functions brought out by specifications of the equipment, the functions to be assigned to the hardware and those to the software are sorted out and the former and the latter are separately designed and organized. The hardware and the software thus organized separately from each other are put together and are caused to operate together, whereby whether the equipment operates in a way to satisfy the specifications is verified.
The ICE 20 is an equipment used for making the above verification, which provides operational environments for the software to be executed and verification supporting functions such as a function to execute sequential instructions step by step and a function to interrupt execution of instructions when certain conditions are met. The ICE 20 also provides, as a hardware function, a function to input to and output from the probe head 18 a signal which is the same as the signal inputted to and outputted from an external terminal of the microcomputer in the equipment under development. Thus, when the probe is connected to the hardware of the equipment under development and the software is executed on the ICE 20, the various operations expected from the microcomputer on the basis of the software are emulated by the ICE 20, so that the same signal as outputted by the terminal of the microcomputer is outputted from the terminal of the probe and the same control as effected by the microcomputer is realized.
In the ICE 20 as described above, the conventional probe of the ICE 20 employs an arrangement wherein its tip portion has a dummy chip 18 (shown in FIG. 4) the shape of which is the same as the shape of the terminal of the microcomputer to be emulated. Where the shapes are the same in this way, the circuit patterns of the target board conductor 12 of the printed circuit board (as shown in FIG. 3) which is a part of the hardware of the equipment under development remain fixed or unchanged. Thus, the purpose of such arrangement is to complete the development of the equipment as a finished equipment by removing the probe of the ICE and then mounting the microcomputer in its place. That is to say, in this arrangement, the operational reliability of the equipment can be ensured because the pattern of the printed circuit after the completion of the verification of the functions of the equipment is in its finished state and undergoes no further changes.
FIG. 3 shows in plan view a plurality of circuit patterns provided on a conventional target board and FIG. 4 shows also in plan view a state in which a dummy chip 16 is soldered on the target board 10 shown in FIG. 1.
As seen in FIG. 3, the leads 14 of the dummy chip 16 are arranged in all four directions and the conductive lines 12 on the target board 10 are electrically connected to the leads 14, respectively.
In the conventional probe of the ICE explained above, it is required that the dummy chip 16 at the foremost end portion of the probe be made in conformity with the shape of the terminal of the microcomputer to be subjected to emulation.
In recent years, kinds of microcomputers have become diversified and, particularly in microcomputers used for control purposes, there is an increasing trend wherein the same function is applied to a plurality of terminal shapes or a given function is added or eliminated depending on needs in the development of equipment.
In order to meet the changing needs in the development of equipment using microcomputers, it is desired that, in the ICE, too, the dummy chip 16 at the foremost end of the probe be improved.
However, since the dummy chip 16 normally employs at its body an engineering plastic and has a terminal portion made of metal foils, it is necessary to make a metal mold specific to the body and make the terminal portion mostly by hand. This is a disadvantage in that the fabrication thereof is not efficient, is costly and involves a long time.
Also, it must be noted that in recent years there is an increasing trend for spaces between terminals of a microcomputer to be reduced, and this makes it impossible to have the dummy chip 16 formed by the conventional method, or if formed, the chip thus formed frequently does not have sufficient strength for practical use.